Automatic flash camera

ABSTRACT

A mechanism for switching from daylight to flash photography and for automatically adjusting the diaphragm aperture to an opening determined by the focusing mechanism. Both the diaphragm aperture and focusing settings are obtained from respective rotating members with a lever riding on a cammed surface of the focusing means and a stop lever mechanism having an angular position determined by the setting of the focusing mechanism. When the brightness of the object is lower than a threshold level, an electromagnet is actuated to cause the stop lever to engage a protrusion on the diaphragm adjustment means thereby stopping the aperture at a setting determined by the focus.

United States Patent Ueda etal.

[54] AUTOMATIC FLASH CAMERA [72] Inventors: Hiroshi \Ueda, Nara;Motonobu Matsuda,

Sakai, both of Japan [73] Assignee: Minolta Camera Kabushiki Kaisha [22]Filed: Feb. 11, 1970 [21] Appl. No.: 10,424

[30] Foreign Application Priority Data Feb. 24, 1969 Japan ..44/l3707[52] U.S. Cl. ..95/l0 CE, 95/1 1.5, 95/53 EB,

[56] References Cited UNITED STATES PATENTS 3,418,904 12/1968 Wick et a1..95/l0 C 3,455,218 7/1969 Eagle et al ..95/10 C [is] 3,654,843 [451Apr. 11, 1972 Primary ExaminerJoseph F. Peters, Jr. Attorney-Watson,Cole, Grindle & Watson [57] ABSTRACT A mechanism for switching fromdaylight to flash photography and for automatically adjusting thediaphragm aperture to an opening determined by the focusing mechanism.Both the diaphragm aperture and focusing settings are obtained fromrespective rotating members with a lever riding on a cammed surface ofthe focusing means and a stop lever mechanism having an angular positiondetermined by the setting of the focusing mechanism. When the brightnessof the object is lower than a threshold level, an electromagnet isactuated to cause the stop lever to engage a protrusion on the diaphragmadjustment means thereby stopping the aperture at a setting determinedby the focus.

6 Claims, 7 Drawing Figures PATENTEDAPR 1 1 I972 SHEET 1 BF 3 FIG.

FIG.2

Sec

IN VENTOR P'ATENTEDAPR 1 I ma 3, 654, 843

sum 2 OF 3 INVENTOR ATTORN PATENTEDA R H I978 3,654, 843

SHEET 3 BF 3 FIG.5 FIG.6

/ ATTORNEY AUTOMATIC FLASH CAMERA BACKGROUND OF THE INVENTION Thepresent invention relates to diaphragm aperture and shutter speedcontrols for cameras and particularly to such controls for cameraprovided with dual acting diaphragm and shutter blades wherein automaticadjustment of the diaphragm aperture and the shutter speed in accordancewith the brightness of an object by means of said diaphragm are effectedfor a changeover from EE photography to automatic flash photography.

Such shutter mechanisms are well known wherein one and the same bladeserves both as a diaphragm and shutter, and with the formation of anaperture, when the light rays of an object entering from the aperturereach a certain level the blades are closed suddenly and a properpre-programmed exposure made by controlling the opening and the openingtime of the blades in accordance with the brightness of the object.

And also, an automatic flash camera is well known wherein the shutteropening time is set for the time suitable for automatic flashphotography and the diaphragm aperture in the camera is fixed inaccordance with the photographic distance for a flash device of acertain guide number.

And, in cameras provided with a programmed shutter using the aforesaiddual diaphragm blades and shutter blades it is desired generally toprovide automatic switching to an automatic flash photography in asimple and reliable manner in accordance with the brightness of anobject.

SUMMARY OF THE INVENTION The present invention relates to an automaticflash adjustment mechanism in cameras of the type specified providedwith an object brightness detection circuit and an electric shuttercircuit comprising an electric delay circuit and a switching circuithaving memory capabilities and assuming a conductive or non-conductivecondition corresponding to a predetermined detection value of the objectbrightness detection circuit. And a stop lever operated by the switchingcircuit is moved back and forth in the moving track of a shuttermechanism, the operating position of the stop lever being interlockedwith the distance set for the camera whereby the diaphragm opening isdetermined in accordance with a focusing mechanism for both daylight andflash photography.

The primary object of the present invention is to provide in a camera ofthe type specified that when the brightness of an object is lower than acertain brightness the electric shutter can be automatically changedover to flash photography and the diaphragm aperture is fixed inaccordance with the correct photographic distance.

A feature of the present invention is to arrange the change overoperation to be carried out by controlling a memory circuit by theoutput from an object brightness detection circuit and an electricshutter circuit before the shutter is operated, wherein the memorycircuit controls a stopper mechanism for a shutter operating ring usedboth for diaphragm and exposure interlocked with the focusing mechanism.

Another feature of the present invention is to control the memorycircuit by controlling the conductive state of an SCR through voltageobtained at the junction of a photoconductive element and a setresistance in the delay circuit of an electric shutter mechanism.

A further object of the present invention is a constant time delaycircuit comprising a set resistance and a condenser in parallel with andaddition to a delay circuit for the electric shutter comprising aphotoconductive element and a condenser, so as to control memory circuitthrough the charging voltage difference of both condensers and at thesame time to operate the switch circuit when the charging voltage of anyone of said both condensers gets to a certain voltage.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is an illustration showing theprogram exposure in a shutter using diaphragm blades and shutter bladesin common in accordance with the present invention.

FIG. 2 is an illustration showing the automatic flash exposure in theshutter shown in FIG. 1.

FIG. 3 is a front view showing the state of the automatic adjustmentmechanism prior to the shutter operation in accordance with the presentinvention.

FIG. 4 is a front view showing the state of the automatic adjustmentmechanism for automatic flash exposure in the embodiment of the shuttershown in FIG. 3.

FIG. 5 is an enlarged front view of a synchro switch mechanism for theembodiment shown in FIG. 4.

FIG. 6 is an enlarged front view of another embodiment of synchro switchmechanism.

FIG. 7 is a wiring diagram in an embodiment of the control circuit inthe present invention.

DESCRIPTION OF THE PREFERRED EMBODIMENT FIG. 1 is a graph showing thediaphragm opening time relationship of a programmed shutter using commondiaphragm blades and shutter blades and the blades carry out relativelyslowly the opening process along straight line G and upon reaching acertain time the blades suddenly close. Therefore in accordance withinclination angle a of straight line G the exposure time-diaphragmopening program is fixed. For example, as shown by point P provided theshutter speed is one one hundred twenty-fifth second the diaphragm is atthe maximum aperture 11. Next, provided the beginning of the closingprocess is one slxtieth second as much as about 2 times as shown bypoint P the diaphragm aperture is at a value of 5.6. In such a shutter,when taking automatic flash photography as shown in FIG. 2, the timefrom the starting of the opening process of the shutter to the startingof the shutter closing process is set for the time suitable for flashphotography for example, one thirtieth second. And, when the openingextent of the diaphragm blades is stopped at a certain aperturecorresponding to the correct photographic distance, for example, 5.6, onhorizontal straight line H and a flash is radiated, as shown by curve Lor L in FIG. 2, to give an exposure.

In FIG. 3 and FIG. 4, blade 1 diaphragm and shutter is only one of, forexample, five blades and connected rotatably to shutter operating ring 2by means of pin 5, and into long slot 3 provided on the tip of blade 1there is fitted pin 4 mounted on the ground plate and through theclockwise rotation of shutter operating ring 2 all the blades are openedand through the counterclockwise rotation they are closed.

The shutter operating ring 2 is biased clockwise by spring 6, andarresting protrusion 7 thereof is rotatably connected to the shuttercase by spindle 12 and engages with open release lever 11 which isbiased counterclockwise through spring 13 wherein the shutter is set asshown in FIG. I. And, protrusion 8 of shutter operating ring 2 pressesagainst the contact piece of electric shutter actuating switch 14, whichis fixed to the ground plate and normally closed and simultaneouslytherewith the other side of said working protrusion 8 engages arm 18 offirst gear 16 biased to rotate clockwise through spring 17in brakinggear system 15. And, on the upper surface of shutter operating ring 2closing driven pin 9 is mounted and on the outer circumference stopperprotrusion 10 is provided.

Electromagnet 19 is controlled by the output from the electric shutterswitching circuit described hereinafter and fixed to the ground plateand provided with armature 21 facing the magnetic pole of electromagnet19. With the auctuate surface 24 of close release lever 20 connectedrotatably by spindle 22 and biased counterclockwise through spring 23,first arm 28 of closing driving lever 25 is connected rotatably to theground plate by spindle 26 and is biased clockwise through strong spring27 and provided with three arms. Second arm 29 protrudes onto shutteroperating ring 2 so as to engage with closing drive pin 9 provided onshutter operating ring 2 and third arm 30 protrudes to the outside ofthe shutter case to serve as a charge lever.

The above formation is similar to known program shutter mechanisms usingcommon diaphragm blades and shutter blades, however, in the presentinvention interlocking lever 31 is connected rotatably to spindle 12 andis biased clockwise through spring 32. Pin 33 provided on one am ofinterlocking lever 31 is arranged to engage with cam surface 41 formedinside of focusing ring 40. Therefore, when the correct photographicdistance is fixed by rotating focusing ring 40, interlocking lever 31swings about spindle 12 as pin 33 moves on cam surface 41. Spindle 34mounted on the other arm of interlocking lever 31, is rotatablyconnected to movable stopper 35 and is biased counterclockwise throughspring 36, and one arm thereof having arresting pawl 37 on its end comesinto contact with rise 44 provided on the end of lever 31, and armature38 formed on the other arm of movable stopper 35 faces electromagnet 39fixed to lever 31. When armature 38 is attracted into contact withelectromagnet 39 and rotates clockwise against spring 36, arresting pawl37 moves into the rotating track of stopper protrusion provided onshutter operating ring 2. Through the engagement of pawl 37 and stopperprotrusion 10 the clockwise rotation of shutter operating ring 2 isrestrained. And, inside of arresting pawl 37 flash trigger switch 42 isformed as shown clearly in FIG. 5, and when arresting pawl 37 engageswith stopper protrusion 10 as described above switch 42 is closed.

Next, with reference to the embodiment of the control circuit inaccordance with the present invention shown in FIG. 7, connecting pointa is in the delay circuit comprising photoconduct'ive element 46connected to power source 45 through actuating switch 14, and delaycondenser 47 is connected to the base of first transistor 50 in theelectric shutter switch circuit. In parallel therewith a constant timedelay circuit K suitable to the flash photographing, for example, of onethirtieth second is formed with set resistance 48 and condenser 49, andconnecting point b thereof is connected to the base of first steptransistor 52. The object brightness detection circuit is composed ofconstant time delay circuit K and the photosensitive delay circuit.

In the electric shutter switch circuit, the collector of first steptransistor 50 is connected to the base of second step transistor 51, andto the collector circuit thereof is connected electromagnet 19 whichtriggers close release lever 20. The collector of transistor 52 havingbase connected to connecting point b is connected to the base of secondstep transistor 51. Therefore, second step transistor 51 is driven tothe conductive state by the switching of either transistor 50 ortransistor 52 so as to operate electromagnet 19. Transistor 53 forms aSchmitt circuit with first transistor 50 or 52 to switch them quicklyand reliably.

Memory circuit M is composed of power source 54, switch 55, resistance56, SCR 57, and electromagnet 39 all arranged in series in the circuit,wherein switch 55 is interlocked with actuating switch 14 through lever11. And, the gate of SCR 57 is connected to the connecting point a inthe delay circuit and the cathode is connected to connecting point b ofthe constant time delay circuit. Therefore when the brightness of anobject is higher than a certain brightness and daylight photography ispossible, the voltage at point a is higher than that at point 12, SCR 57is non-conductive, memory circuit M remains in the non-conductive state,and electromagnet 39 is held in a demagnetizing state.

And, when the brightness of an object is lower than a certain brightnessand the flash photography is required, the volt age at point b is higherthan that at point a, SCR 57 is conductive, memory circuit M is in theconductive state, and electromagnet 39 is excited to rotate movablestopper 35 clockwise.

The flash circuit is composed of the charging circuit including powersource 58 and condenser 59, and the discharging circuit including flashdischarge lamp 60 connected to condenser 59. And, the positive pole oftrigger condenser 63 is connected to power source 58 through switch 42and the primary winding of boosting transformer 62 is connected toterminal C and to the anode side of SCR 57 in memory circuit M. Thenegative pole of trigger condenser 63 is connected through terminal d tothe cathode side of SCR 57. One end of the secondary winding of saidboosting transformer 62 is connected to trigger electrode 61 of flashdischarge tube 60.

The present invention is formed as described above, therefore, when thebrightness of an object is suitable for photography, through theclockwise rotation of open release lever 11 and the engagement thereofwith arresting protrusion 7 of shutter operating ring 2 is broken, andring 2 starts to rotate clockwise through spring 6, actuating switch 14and switch 55 are closed.

By closing actuating switch 14 the object brightness detection circuitcomposed of the photosensitive delay circuit and constant time delaycircuit K is made operative, however, in this case since the currentrunning through photoconductive element 46 is larger than the currentrunning through set resistance 48, the charging of condenser 47 isalways higher than the charging of condenser 49 and the voltage atconnecting point a is higher than the voltage at connecting point 1:,SCR 57 remains in the non-conductive state and memory circuit M is inthe non-conductive state, so that electromagnet 39 is in thenon-conductive state and movable stopper 35 is in a position forengaging with riser 44 through spring 36. Therefore, shutter operatingring 2 rotates without restriction while operating braking gear system15, and blade 1 carries out the opening process along oblique line Gshown in FIG. 1.

When the charging voltage of condenser 47 gets to a certain voltage,first step transistor 50 in the electric shutter switching circuitswitches and thereby second step transistor 57 becomes conductive andelectromagnet 19 is excited, so that close release lever 20 is attractedto rotate clockwise against spring 23, and close driving lever 25 isarrested on arcuate surface 24 of said close release lever 20 rotatesclockwise, quickly by the action of strong spring 27. Second arm 29comes into contact with close drive pin 9 mounted on shutter operatingring 2 to repulse it counterclockwise against spring 6, so that blade 1is suddenly closed and accordingly the exposure is finished through theexposure time and diaphragm programmed in accordance with the brightnessof the object and daylight EE program photography is effected.

On the contrary, if the brightness of an object is lower than a certainbrightness and flash photography is required, by rotating focusing ring40 to fix the correct photography distance interlocking lever 31 is,rotated by cam 41 and corresponding thereto the position of rotaryspindle 34 of movable stopper 35 is fixed. On the other side, byrotating open release lever 11 clockwise shutter operating ring 2 startsto rotate in the same manner as described above and actuating switch 14and switch 55 interlocked therewith in circuit M are closed. And, inthis case the current running through set resistance 48 is larger thanthe current running through photoconductive element 46 so that condenser49 is charged the higher voltage than the condenser 47 and the voltageat connecting point b becomes higher than the voltage at connectingpoint a. Thereby, SCR 57 and memory circuit M are switched to theconductive state. Therefore, electromagnet 39 is excited, movablestopper 35 is attracted to rotate clockwise against spring 36, and inthe position corresponding to spindle 34 thereof arresting pawl 37 ismoved into the rotation track of stopper protrusion 10. Therefore, whenstopper protrusion 10 engages with arresting pawl 37 the rotation ofshutter operating ring 2 is restrained as shown in F IG. 4 and theopening process of blade 1 is stopped. The diaphragm aperture is in afixed position following horizontal line H from oblique line G shown inFIG. 2. And, simultaneously with the engagement of stopper protrusion 10and arresting pawl 37 flash trigger switch 42 is closed and terminals c,d of the flash circuit are energized so that trigger condenser 63 isdischarged and a high voltage is impressed on trigger electrode 61 offlash discharge lamp 60 by transformer 62 to flash discharge tube 60 asshown by curve L in FIG. 2. And, when condenser 49 gets to a certainvoltage transistor 52 switches, transistor 51 is made conductive, andthe shutter closing process is carried out. Accordingly flashphotography wherein the setting a diaphragm aperture in accordance withthe correct focusing distance is effected quite automatically.

FIG. 6 shows another embodiment of the flash trigger switch, whereincontact 42' is positioned to contact with close driving lever 25 and isclosed simultaneously with the actuation of close driving lever 25. Inthis case tube is lit to irradiate as shown by curve L We claim:

I. A diaphragm aperture and flash control mechanism for a camera of thetype having common diaphragm and shutter blade mechanisms, comprising:

a rotating member for determining the size of the diaphragm aperture inaccordance with the angular position thereof;

means for driving said rotating member to determine said aperture size;

shutter closing means for returning said rotating member from a givenangular position to an initial position to close said aperture:

means for focusing the objective lens of said camera;

means for stopping said rotating member in an angular position relativeto the setting of said means for focusing;

means for sensing the brightness of an object and for comparing theobject brightness with a predetermined level;

means for moving said means for stopping into engagement with saidrotating member with the brightness of an object lower than saidpredetermined level; and

means for triggering said flash circuit only with said rotating memberstopped in said angular position.

2. A diaphragm aperture and flash control mechanism as in claim 1,wherein said means for focusing has a cam surface;

said rotating member has a stopper protrusion;

said means for stopping includes an interlocking lever engaging said camsurface so as to be moved in accordance with the means for focusing;

a stop lever movably mounted on said interlocking lever and having anarmature and an extending arm;

in FIG. 2.

the flash discharge said means for moving includes an electromagnetmounted on said interlocking lever;

means for exciting said electromagnet with the object brightness lowerthan said predetermined level; and

said stop lever is moved by the attraction of said armature to saidelectromagnet with the excitation thereof to engage said protrusion andsaid extending arm.

3. A diaphragm aperture and flash control mechanism as in claim 2,wherein said means for triggering is closed with said protrusion andsaid extending arm in engagement with one another.

4. A diaphragm aperture and flash control mechanism as in claim 1,wherein said means for triggering is closed with the actuation of saidshutter closing means.

5. A diaphragm aperture and flash control mechanism as in claim 1,wherein said means for moving includes a detecting circuit having aphotoelectric element for determining the object brightness, an electricpower source, and a switching means disposed between said electromagnetand said electric power source and connected to said detecting circuit;and said switching means is closed with the object brightness lower thansaid predetermined level.

6. A diaphragm aperture and flash control mechanism as in claim 5,wherein said detecting circuit includes a first delay circuit having aphotoconductive element and a first condenser connected in series withone another at a first connecting point, and a second delay circuithaving an ohmic resistor and a second condenser connected in series withone another at a second connecting point; and

said switching means includes a silicon control rectifier connected tosaid first and second connecting points to be conductive with theelectric potential at said first connecting point lower than at saidsecond point.

1. A diaphragm aperture and flash control mechanism for a camera of thetype having common diaphragm and shutter blade mechanisms, comprising: arotating member for determining the size of the diaphragm aperture inaccordance with the angular position thereof; means for driving saidrotating member to determine said aperture size; shutter closing meansfor returning said rotating member from a given angular position to aninitial position to close said aperture: means for focusing theobjective lens of said camera; means for stopping said rotating memberin an angular position relative to the setting of said means forfocusing; means for sensing the brightness of an object and forcomparing the object brightness with a predetermined level; means formoving said means for stopping into engagement with said rotating memberwith the brightness of an object lower than said predetermined level;and means for triggering said flash circuit only with said rotatingmember stopped in said angular position.
 2. A diaphragm aperture andflash control mechanism as in claim 1, wherein said means for focusinghas a cam surface; said rotating member has a stopper protrusion; saidmeans for stopping includes an interlocking lever engaging said camsurface so as to be moved in aCcordance with the means for focusing; astop lever movably mounted on said interlocking lever and having anarmature and an extending arm; said means for moving includes anelectromagnet mounted on said interlocking lever; means for excitingsaid electromagnet with the object brightness lower than saidpredetermined level; and said stop lever is moved by the attraction ofsaid armature to said electromagnet with the excitation thereof toengage said protrusion and said extending arm.
 3. A diaphragm apertureand flash control mechanism as in claim 2, wherein said means fortriggering is closed with said protrusion and said extending arm inengagement with one another.
 4. A diaphragm aperture and flash controlmechanism as in claim 1, wherein said means for triggering is closedwith the actuation of said shutter closing means.
 5. A diaphragmaperture and flash control mechanism as in claim 1, wherein said meansfor moving includes a detecting circuit having a photoelectric elementfor determining the object brightness, an electric power source, and aswitching means disposed between said electromagnet and said electricpower source and connected to said detecting circuit; and said switchingmeans is closed with the object brightness lower than said predeterminedlevel.
 6. A diaphragm aperture and flash control mechanism as in claim5, wherein said detecting circuit includes a first delay circuit havinga photoconductive element and a first condenser connected in series withone another at a first connecting point, and a second delay circuithaving an ohmic resistor and a second condenser connected in series withone another at a second connecting point; and said switching meansincludes a silicon control rectifier connected to said first and secondconnecting points to be conductive with the electric potential at saidfirst connecting point lower than at said second point.